Embedded devices generally comprise objects that contain an embedded computing system, which may be enclosed by the object. The embedded computer system may be designed with a specific use in mind, or the embedded computer system may be at least in part general-purpose in the sense that a user may be enabled to install software in it. An embedded computer system may be based on a microcontroller or microprocessor CPU, for example.
Embedded devices may comprise one or more processors, user interfaces and displays, such that a user may interact with the device using the user interface. The user interface may comprise buttons, for example. An embedded device may comprise a connectivity function configured to communicate with a communications network, such as, for example, a wireless communications network. The embedded device may be enabled to receive from such a communications network information relating to, for example, a current time and current time zone.
More complex embedded devices, such as cellular telephones, may allow a user to install applications into a memory, such as, for example, a solid-state memory, comprised in the device. Embedded devices are frequently resource-constrained when compared to desktop or laptop computers. For example, memory capacity may be more limited than in desktop or laptop computers, processor computational capacity may be lower and energy may be available from a battery. The battery, which may be small, may be rechargeable.
Conserving battery power is a key task in designing embedded devices. A lower current usage enables longer time intervals in-between battery charging. For example, smartphones benefit greatly when they can survive an entire day before needing recharging, since users are thereby enabled to recharge their phones overnight, and enjoy uninterrupted use during the day.
Battery resources may be conserved by throttling a processor clock frequency between a maximum clock frequency and a lower clock frequency, for example one half of the maximum clock frequency. Another way to conserve battery power is to cause a display of an embedded device to switch itself off then the device is not used, since displaying content on a display consumes energy in order to cause the display to emit light that humans can see.